The Multipurpose Arthritis Center at the University of North Carolina in Chapel Hill consists of a Biomedical Research Component, a Non-Biomedical Research Component, an Immunology Core, a Numerical Sciences Core, and an Administrative Core. Areas of special emphasis in the Biomedical Component include: molecular and functional studies of autoantibodies in SLE and related diseases; basic mechanisms in murine models of autoimmunity; the genetics and idiotypy of rheumatoid factor and other autoantibodies; the molecular biology of the MHC; characterization of cellular activation antigens; the structure and cell biology of complement receptors; B cell differentiation; complement and disease; autoimmunity to collagen: bacterial cell wall constituents as triggers and activators of erosive synovitis; and oncogenes and autoimmunity. Five Developmental and Feasibility projects are proposed. Four are molecular biology/genetic investigations of basic questions in autoimmunity or inflammation. The fifth will test the feasibility of developing a novel and potentially useful new model of reactive arthritis in monkeys. Building upon a strong base in education and community activities, the Non-Biomedical Research Component proposes six projects. Two projects focus on the education of medical students in rheumatol- ogy. Two projects are behavioral theory-based investigations of patients with arthritis, continuing a tradition of social and behavioral research in this Component. One project examines the clinical encounter between physicians and patients, with the goal of improving patient-doctor communication. The final project concerns arthritis work disability in a rural southern community, and reflects a major focus on community-based epidemiological research. Already-funded laboratory research will be supported by an Immunology Core, which will develop and maintain immunological and scientific databases, produce monoclonal antibodies, support a HPLC facility, provide flow cytometry, and maintain a pathogen- free inbred mouse colony. A Numerical Sciences Core will support research efforts in the Non-Biomedical Component with respect to research design and methodology, data collection, project participant registry, data processing, database management, and data analysis. The Administrative Core will provide overall coordination and support of MAC activities, perform internal review, and assure optimum liaison within the University and in the community.